Unsuspecting motorists will curse their GPS systems, roads will turn into parking lots and a major artery to the nation’s most populous city will be blocked.

New Jersey, this is going to hurt.

Tomorrow is the start of the first workweek without the Pulaski Skyway as an option to get to Jersey City or Manhattan.

The two northbound lanes of the iconic but decrepit 3½-mile-long bridge between Newark and Jersey City will be closed for two years while the Skyway undergoes a major rehabilitation. A study by a Stevens Institute of Technology professor in nearby Hoboken predicts the commute time for an average person will increase by 30 to 40 percent.

GPS systems will be rendered useless for people traveling Routes 1&9 north in the area of the Skyway. One of Tony Soprano’s preferred paths to the city will be detoured for the next 24 months — and the real-life commuters who travel in 34,000 vehicles a day will have to find a new route.

“It’s going to be very difficult. That’s a very important artery,” state Transportation Commissioner Jim Simpson said. “We’re trying to prepare for the worst and hope for the best, but it’s not going to be easy. On a good day, when everything works, it (the Skyway) is difficult.”

A team led by Jose Emmanuel Ramirez-Marquez, an associate professor at Stevens’ School of Systems and Enterprises, simulated congestion on Skyway alternate routes and determined the average commuting time would increase by 30 to 40 percent.

“This is a best-case scenario,” Ramirez-Marquez said. “It can be worse. It can be much worse.”

His prediction for tomorrow?

“A lot of pain.”

But traffic was flowing yesterday, the first day of the closure, according to a live blog updated throughout the afternoon by The Jersey Journal.

The research by Ramirez-Marquez’s team found that the additional commuting time increase could result in a loss of more than $750 million in wage hours over the two years. They factored in the New Jersey average hourly salary of $19.10, the average gas price of $3.34 a gallon and an average delay of 30 percent.

Two southbound lanes from New York to New Jersey will remain open during the $1 billion project, which calls for the rehabilitation of the bridge deck and the replacement of deteriorating beams.

Last week, Simpson showed a scary sight under the 82-year-old steel-truss bridge. As motorists traveled above, Simpson was under the span on a bucket truck, pointing to holes that rotted through the rusted steel I-beams.

He said if repairs were delayed further, “we could lose this bridge.”

That’s why transportation officials say the time has come to tear off the Band-Aid and get this over with.

Travel alternatives to the northbound Pulaski Skyway include the New Jersey Turnpike extension on Interstate 78 east in Hudson County — where the shoulder has opened as a third lane during rush hours — and also Truck Routes 1&9.

NJ Transit also has added extra rush-hour trains on the Morris and Essex and North Jersey Coast lines, plus more train cars on the Raritan Valley Line.

“I’m going to see how it sorts out,” said commuter Kevin Willens, who travels to Jersey City and Manhattan from Millburn. “I’m optimistic that a new equilibrium will be established.”
There’s at least one alternate route he will try to steer clear of.

“1&9 (Truck), I’ve taken a lot of times as the alternate route, and it gets backed up — it’s terrible,” Willens said.

He said he will pay attention to real-time traffic updates to find out how long it would take him to drive to Jersey City.

“If it says an hour, I’ll go take the train,” Willens said.

Balancing out some of the commuting pain, one of the two lanes leading from the Holland Tunnel to the westbound Turnpike extension in Hudson County is closing for a year and a half while a contractor rehabilitates and repairs the extension between the approach to the tunnel and Exit 14C, Turnpike officials said.

Engineers considered keeping open the Pulaski Skyway to one lane of travel in each direction, but figured the bridge was too narrow. They also thought about alternating the direction of travel to coincide with the morning and evening rush hours, but said halting cars and moving the barriers would have been problematic.

So they opted to keep the Skyway open only for the two southbound lanes from New York to New Jersey during the construction.

After those two lanes are rehabilitated, traffic will shift to those lanes while the two others are rehabilitated — but the direction of travel will always be south during the project, officials said.

New Jersey transportation officials are working with the trucking industry to encourage deliveries in off-peak hours, Simpson said.

He said that with the Passover seder tomorrow and then Good Friday closing schools in Jersey City at the end of the week, the full extent of the traffic patterns might not be known until next week.

“The true test will probably be the week after Easter Sunday,” Simpson said. “I can assure you that the first month is going to be very difficult.”